Background Image 2 - (Kratochvil, n.d.)
Figure 4 - (Michaud, 2014)
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OpencastOpencast mining is a method predominantly used to utilise low yield ore bodies with mining of the ore taking place at the bottom of the pit (Mine-engineer.com, n.d.). Opencast mining is characterised by high tonnage mining rates with some mines reaching up to 100,000 tonnes per day. Opencasts are most recognisable by the large pit where materials have been excavated in order to reach the ore. This material is then placed in a waste dump and the ores are then crushed and concentrated and some mines will use leaching to extract even more materials from the ores (Dunbar, 2012).
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Figure 5 - (WOW.com, 2016)
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SubsurfaceSubsurface mining is commonly associated with deep, high grade ores with lower tonnage rates around 20,000 tonnes per day. This method has many different iterations including:
Cut and Fill – Ore is mined horizontally, gradually moving upwards by filling the void left by the ore body with waste rock and cement. Narrow Vein – Used for veins or ore as narrow as half a metre wide, such narrow veins can be mined manually however this is expensive and will usually only be used to extract very high grade ore. Stoping – A competent ore and ore body with a footwall steeper than the angle of repose is blasted into a pile of “muck” and excavated from there. Soft ores such as potash can be simply ground away from the working wall (Dunbar, 2012). |
Figure 6 - (Straterra, n.d.)
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SeabedSeabed mining is a new proposal for extracting high yield ores from sea floor sources such as “seafloor massive sulphides” (cited from Schmidt, 2015) near mid-ocean ridges. A proposed technique for extraction includes the use of vacuums on polymetallic nodules in seafloor sediment. Such resources that could be extracted from this method include cobalt, copper and rare-earths (Schmidt, 2015).
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